Transmitter position integrity checking

ABSTRACT

The subject matter disclosed herein relates to determining whether a reported position of a wireless transmitter is sufficiently accurate in accordance with an accuracy metric based at least in part on a calculated range between an estimated position of a mobile station and the reported position and also based at least in part on one or more measurements taken from one or more signals transmitted by the wireless transmitter.

BACKGROUND

1. Field

The subject matter disclosed herein relates to integrity checkingreported positions of wireless transmitters.

2. Information

The position of a mobile station, such as, for example, a cellulartelephone, may be estimated based on information gathered from varioussystems. One such system may comprise a satellite positioning system(SPS) that may comprise a number of satellite vehicles (SV) orbiting theearth. Another example of a system that may provide a basis forestimating the position of a mobile station is a terrestrial wirelesscommunications system, such as, for example, a cellular communicationssystem, that may comprise a number of wireless transmitters to supportcommunications for a number of mobile stations.

A position estimate, which may also be referred to as a position “fix”,for a mobile station may be obtained based at least in part on distancesor ranges from the mobile station to one or more transmitters, and alsobased at least in part on the locations of the one or more transmitters.The transmitters may comprise SVs in the case of an SPS, and/orterrestrial wireless transmitters in the case of a cellularcommunications system, for example. The locations of the wirelesstransmitters may be ascertained, in at least some cases, frominformation provided by the wireless transmitters themselves and/or frominformation stored in an almanac, for example.

SUMMARY

In an aspect, a reported position associated with a wireless transmittermay be received at a mobile station. A position of the mobile stationmay be fixed at a first point in time, and a range between the reportedposition associated with the wireless transmitter and the estimatedposition of the mobile station may be calculated. A determination may bemade as to whether the reported position associated with the wirelesstransmitter is sufficiently accurate for a given application, whereinthe determination may be based at least in part on the calculated rangeand based at least in part on one or more measurements related to one ormore signals transmitted by the wireless transmitter at approximatelythe first point in time.

BRIEF DESCRIPTION OF THE FIGURES

Non-limiting and non-exhaustive examples will be described withreference to the following figures, wherein like reference numeralsrefer to like parts throughout the various figures.

FIG. 1 is a schematic block diagram of an example satellite positioningsystem (SPS) and an example wireless communications system.

FIG. 2 is an illustration depicting an example base station almanacserver in communication with a number of mobile stations via one or morewireless communication networks.

FIG. 3 is an illustrative schematic diagram of a wireless transmitterand a plurality of mobile stations.

FIG. 4 is a flow diagram of an example process for checking theintegrity of a reported position of a wireless transmitter.

FIG. 5 is a flow diagram of an example process for adjusting anuncertainty value for a reported position of a wireless transmitter.

FIG. 6 is a schematic block diagram depicting an example mobile station.

FIG. 7 is a schematic block diagram of an example computing platform.

DETAILED DESCRIPTION

Reference throughout this specification to “one example”, “one feature”,“an example” or “a feature” means that a particular feature, structure,or characteristic described in connection with the feature and/orexample is included in at least one feature and/or example of claimedsubject matter. Thus, the appearances of the phrase “in one example”,“an example”, “in one feature” or “a feature” in various placesthroughout this specification are not necessarily all referring to thesame feature and/or example. Furthermore, the particular features,structures, or characteristics may be combined in one or more examplesand/or features.

As discussed above, the position of a mobile station, such as, forexample, a cellular telephone, may be estimated based on informationgathered from various systems, including SPS and cellular communicationssystems, for example. A position estimate for a mobile station may beobtained based at least in part on distances or ranges from the mobilestation to one or more transmitters, and also based at least in part onthe locations of the one or more transmitters. The transmitters maycomprise SVs in the case of an SPS, and/or terrestrial wirelesstransmitters, often referred to as base stations, in the case of acellular communications system, for example. The locations of thewireless transmitters may be ascertained, in at least some cases, frominformation provided by the wireless transmitters themselves and/or frominformation stored in an almanac, for example.

However, in at least some cases, the position of a wireless transmittermay not be accurately reported by the wireless transmitter and/or by abase station almanac server. For example, a position may be reportedthat may refer to a center of a coverage area for the wirelesstransmitter rather than referring to the location of the wirelesstransmitter's antenna. For another example, the reported position mayrefer to the position of the antenna, but may be inaccurate due to anyof a number of reasons. Inaccuracies in a reported position for awireless transmitter may result from, for example, human and/or machineerrors in calculating and/or storing the transmitter location.Inaccuracies may further result from deliberate misreporting of aposition with the intent of spoofing a position location system, forexample.

As described in connection with various aspects of the examples thatfollow, the integrity and/or reliability of a reported position for awireless transmitter may be assessed by checking the reported positionagainst mobile station position information and against wirelesstransmitter signal measurement information. In an aspect, the signalmeasurement information may be gathered and/or generated by one or moremobile stations receiving one or more signals from the wirelesstransmitter. In another aspect, information may be gathered at a numberof locations in order to refine an uncertainty value that may beassigned to a reported transmitter location. The uncertainty value maybe indicated using any suitable scale or numbering system and may beused in future measurements involving the transmitter in order tocorrect for errors in the reported position.

For one example, a reported position associated with a wirelesstransmitter may be received at a mobile station. The position may bereported by the wireless transmitter itself, or in another aspect may bereported by a base station almanac server, for example. A position ofthe mobile station may be estimated at a first point in time, and arange between the reported position associated with the wirelesstransmitter and the estimated position of the mobile station may becalculated. A determination may be made as to whether the reportedposition associated with the wireless transmitter is sufficientlyaccurate in accordance with an accuracy metric for a given applicationsuch as, for example, estimating positions for mobile stations. Thedetermination may be based at least in part on the calculated range andfurther based at least in part on one or more measurements related toone or more signals transmitted by the wireless transmitter and receivedby a mobile station at approximately the first point in time. Themeasurements, in an aspect, may be obtained from code phase detections,for example, although the scope of claimed subject matter is not limitedin this respect. As used herein, the term sufficiently accurate inaccordance with an accuracy metric refers to meeting or exceeding athreshold level of accuracy appropriate for a given application. Forexample, if a given application for obtaining a position estimate for amobile station specifies that the position estimate should be accurateto within, e.g., two meters, the threshold level of accuracy for areported position of a wireless transmitter may be selected to ensurethat any error in a reported position associated with a wirelesstransmitter would not result in an error in the estimated position forthe mobile station exceeding two meters. Another application may specifythat the reported position associated with the wireless transmitter tobe accurate to within, e.g., 0.5 meters, or 1 meter, or 5 meters, or 10meters, or 20 meters, etc. Of course, these are merely examples of anapplication and of a threshold level of accuracy, and the scope ofclaimed subject matter is not limited in these respects.

In another aspect, a degree of disagreement between a calculated rangeto a wireless transmitter and a measured range to the wirelesstransmitter may be referred to as a residual error. The calculated rangemay be based in part on a reported position of the wireless transmitter,and the measured range to the wireless transmitter may be based onmeasurements observed from one or more signals transmitted by thewireless transmitter, for example. A plurality of residuals may bedetermined at a plurality of mobile station positions, in an aspect, andthe bias and spread of the plurality of residuals may be used to derivean uncertainty value assigned to the reported transmitter location. Suchan uncertainty value may be used for future measurements involving thewireless transmitter, for example, in order to correct for errors in thereported position. These aspects, and others, are described in moredetail in the following discussion.

FIG. 1 is an illustrative schematic block diagram of an SPS 110 and acellular network 120 in communication with a mobile station 150.Cellular network 120, for this example, may provide voice communicationfor a number of mobile stations including mobile station 150, forexample, and may further support estimating a position for the mobilestations in addition to providing voice communication. Cellular network120 may comprise any of a number of cellular network types, severalexamples of which are described below. Cellular network 120 for thisexample comprises base stations 132, 134, and 136 that providecommunication for a number of wireless terminals, such as, for example,mobile station 150. For simplicity, only a few base stations 132, 134,and 136 are depicted and one mobile station 150 is depicted in FIG. 1.Of course, other examples may include additional numbers of basestations and/or mobile stations, and the configuration depicted in FIG.1 is merely an example configuration. Also, cellular network 120 ismerely an example wireless communications system, and the scope ofclaimed subject matter is not limited in this respect.

As used herein, the term base station is meant to include any wirelesscommunication station and/or device installed at a fixed location andused to facilitate communication in a wireless communications system,such as, for example, a cellular network, although the scope of claimedsubject matter is not limited in this respect. Also, as used herein, theterms wireless transmitter and base station are synonymous, and may beused interchangeably. In another aspect, base stations may be includedin any of a range of electronic device types. In an aspect, a wirelesstransmitter may comprise a wireless local area network (WLAN) accesspoint, for example. Such a WLAN may comprise an IEEE 802.11x network inan aspect, although the scope of claimed subject matter is not limitedin this respect. In another aspect, a wireless transmitter may comprisea femtocell.

As used herein, the term mobile station (MS) refers to a device that mayfrom time to time have a position location that changes. The changes inposition location may comprise changes to direction, distance,orientation, etc., as a few examples. In particular examples, a mobilestation may comprise a cellular telephone, wireless communicationdevice, user equipment, laptop computer, other personal communicationsystem (PCS) device, personal digital assistant (PDA), personal audiodevice (PAD), portable navigational device, and/or other portablecommunication devices. A mobile station may also comprise a processingunit and/or computing platform adapted to perform functions controlledby machine-readable instructions.

In an aspect, SPS 110 may comprise a number of SVs, for example SVs 112,114, and 116. For an example, SPS 110 may comprise SVs in any one ofseveral global navigation satellite systems (GNSS) such as, for example,Global Positioning System (GPS), Glonass, Galileo, to name but a fewexamples, although the scope of claimed subject matter is not limited inthis respect. In one or more aspects, mobile station 150 may receivesignals from one or more of SVs 112, 114, and 116, and may alsocommunicate with one or more of base stations 132, 134, and 136. Forexample, mobile station 150 may obtain one or more measurements from oneor more signals received from one or more of SVs 112, 114, and 116,and/or base stations 132, 134, and 136 in order to estimate a positionfor mobile station 150. In some situations, if sufficient SVs areviewable by mobile station 150, a position estimate for mobile station150 may be obtained based on signals received from several SVs of SPS110. In at least some circumstances, such a position estimate may bebased on signals from four or more SVs in SPS 110.

If insufficient SVs are viewable by mobile station 150, one or moresignals from terrestrial wireless transmitters such as base stations132, 134, and/or 136, for example, may supplement the signals receivedfrom SPS 110 in order to enable estimating a position of mobile station150. In other examples, the position estimate may be based entirely onsignals from terrestrial wireless transmitters. Mobile station 150 mayestimate its position based, at least in part, on measurementinformation obtained from one or more signals received from one or moreof base stations 132, 134, and/or 136. The position estimate may furtherbe based, at least in part, on reported positions of the base stations.

As previously mentioned, positions of base stations 132, 134, and/or 136may be reported by the base stations themselves to mobile station 150,or in other cases may be provided as part of a base station almanac 185provided by a base station almanac server 180, for example. In oneaspect, mobile station 150 may use the received base station almanac 185in conjunction with measurements obtained from signals received from oneor more of base stations 132, 134, and/or 136, perhaps in addition tomeasurements involving signals received from other transmitters notshown in FIG. 1, to estimate a position of the mobile station. In anaspect, the position of mobile station 150 may be estimated through atrilateration operation, to name an example technique. If any of thereported positions of the base stations are inaccurate, the inaccuracywill be reflected in the estimated position of mobile station 150. Anamount of error in the estimated position of mobile station 150 may bebased at least in part on an amount of error in the reported basestation positions. Techniques for evaluating the accuracy of reportedbase station positions are discussed more fully below.

In another aspect, operations to estimate a position for mobile station150 may be performed by a network entity such as, for example, locationserver 170 depicted in FIG. 1, rather than at mobile station 150. Here,location server 170 may include any one of several systems including,for example, a position determination entity (PDE). Such a positionestimate may be based, at least in part, on information gathered bymobile station 150 from one or more of base stations 132, 134, and/or136, as described above. In a further aspect, location server 170 maytransmit the estimated position to mobile station 150.

A mobile switching center (MSC) 140 for this example may be coupled tobase stations 132, 134, and 136, and may further couple to other systemsand networks, such as a public switched telephone network (PSTN), apacket data serving node (PDSN) 160, and so on. MSC 140 for this exampleprovides coordination and control for the base stations coupled to itand further controls the routing of data to/from the mobile stationsserved by these base stations. For the example depicted in FIG. 1, PDSN160 may couple MSC 140 to location server 170 and to a base stationalmanac (BSA) database server 180. Location server 170 may collect andformat location data, may provide assistance to mobile stations toestimate positions of the mobile stations, and/or may performcomputations to obtain position estimates for the mobile stations. BSAdatabase server 180 may manage a BSA database 185, which for thisexample stores a base station almanac for cellular network 110.

The term base station almanac (BSA) as used herein is meant to includeany organized set of information related to a plurality of transmittersof a wireless communications network. A base station almanac may bestored in a memory of a computing platform, such as BSA database server180, for example, or in a memory of mobile station 150, for anotherexample. In another aspect, the base station almanac may be transmittedfrom BSA database server 180 to mobile station 150. In a further aspect,a subset of a BSA stored at BSA database server 180 may be transmittedto mobile station 150.

In one aspect, mobile station 150 may use the received BSA informationto obtain a position estimate, for example by trilateration usinginformation and measurements from a number of transmitters.

FIG. 2 is an illustration depicting a wireless communications network230 comprising an example base station almanac server 250 incommunication with a number of mobile stations 222 and 224 via one ormore wireless communications networks 232 and 234 and via Internet 240.For this example, mobile station 222 represents a multi-mode device thatmay support communication with both a packet-switched wireless localarea network (WLAN) 232 and a cellular network 234. Of course, these aremerely examples of the types of wireless communications networks withwhich a multimode device may communicate, and the scope of claimedsubject matter is not limited in this respect. Also for this example,mobile station 224 represents a single-mode device that may supportcommunication with cellular network 234. Again, the cellular network ismerely one example of a wireless communications network with which amobile station may establish communication.

FIG. 2 further depicts a number of example transmitter types 210 thatmobile stations 222 and 224 may monitor. Mobiles stations 222 and 224may or may not be subscribed to any given network associated with thevarious respective transmitter types to be able to monitor signalstransmitted from the various transmitter types. Therefore, BSAinformation provided to the mobile stations may or may not includeinformation associated with networks to which the mobile stations arenot subscribed. In one aspect, BSA information may include informationassociated with transmitters that are part of networks to which one ormore of mobile stations 222 and/or 224 are not subscribed. In thismanner, either of mobile stations 222 and/or 224 may estimate itslocation using at least some signals from networks to which they are notsubscribed. However, as mentioned previously, positions that arereported for the various transmitters may or may not be reliable.Techniques for evaluating whether reported transmitter locations aresufficiently accurate for a given application are disclosed herein.Additionally, techniques for compensating for errors in reportedtransmitter locations are also described herein.

In another aspect, BSA database server 250 may obtain a BSA databasefrom an external BSA source 260. For example, a cellular networkprovider may contract with a third party to develop and provide BSAinformation to BSA database server 250. In a further aspect, BSAdatabase server 250 may receive BSA information from mobile stations 222and/or 224 as the mobile stations develop such information at least inpart through monitoring signals transmitted from one or more of exampletransmitters 210.

Although the example of FIG. 2 depicts two mobile stations, in practicea wide variety of mobile station types exhibiting a wide range ofdifferent functionalities and/or storage capabilities may be utilized tocommunicate with a large variety of potential network types. Further,the mobile stations may exhibit a wide range of different usagepatterns. Also, the types of transmitters depicted for transmitters 210are merely example types, and the scope of claimed subject matter is notlimited in this respect.

FIG. 3 is a schematic diagram of example wireless transmitter (e.g.,base station) 132 and a plurality of mobile stations 310, 320, 330, and340. For the example of FIG. 3, base station 132 may report a positionassociated with base station 132 by periodically transmitting theposition information. In some situations, base station 132 may report apurported position of one or more antennas associated with base station132. However, it is also possible that the position reported by basestation 132 may refer to a center of a coverage area, for example,rather than to a position of an antenna. In another aspect, base station132 may report the position associated with base station 132 in responseto receiving a request from a mobile station. In another example, theposition associated with base station 132 may be reported by anothernetwork entity, such as a location server such as server 170 of FIG. 1,described above. In an aspect, a reported position associated with basestation 132 may be received by mobile stations 310, 320, 330, and 340,for this example.

In order to ascertain whether a reported position associated with basestation 132 sufficiently accurately represents the position of atransmitting antenna in accordance with an accuracy metric for a givenapplication, mobile station 310 may estimate its own position (x1, y1,z1) at a first point in time, t1, where “x” represents longitude, “y”represents latitude, and “z” represents altitude. Example coordinatesystems that may be used include the World Geodesic System (WGS-84) andthe Earth-Centered, Earth-Fixed (ECEF) coordinate system, although thescope of claimed subject matter is not limited in this respect. Mobilestation 310 may estimate its location using any of a variety oftechniques, including, to name but one example, the use of signalsreceived from an SPS. For another example, mobile station 310 mayestimate its position at least in part by using signals received fromother terrestrial wireless transmitters whose locations are thought tobe sufficiently accurately reported. In another aspect, operations toestimate a position of mobile station 310 may be performed at a locationserver such as server 170 depicted in FIG. 1. However, the scope ofclaimed subject matter is not limited in this respect.

In a further aspect, a range between the reported position associatedwith base station 132 and the estimated position of mobile station 310may be calculated. Any of a number of well known techniques may beutilized to calculate the range between the reported position associatedwith base station 132 and the estimated position of mobile station 310.

To determine whether the reported position associated with base station132 is sufficiently accurate, mobile station 310 may obtain one or moremeasurements from one or more signals transmitted by base station 132 atapproximately the first point in time, t1. If the obtained measurementscorrelate relatively strongly with the calculated range, the reportedposition associated with base station 132 may be considered to be atleast sufficiently accurate. In other words, the reported positionassociated with base station 132 may be considered to be reasonable, andthere may be considered to be a high degree of agreement between thecalculated range and the obtained measurements. In another aspect, ifthe obtained measurements correlate strongly, it may be assumed that thereported position is that of the base station antenna, rather than thatof some other position such as a center of a coverage area, for example.

The types of measurements that mobile station 310 may obtain for the oneor more signals transmitted by base station 132 at approximately thefirst point in time may include, but are not limited to, timingparameter(s) and/or strength for at least one of the signals transmittedby the base station 132 and received at mobile station 310, for example.Timing parameters may include, for example, one or more of a phasemeasurement and/or a round trip propagation delay. However, these aremerely examples of timing parameters, and the scope of claimed subjectmatter is not limited in this respect.

In addition to timing parameters and the calculated range between thereported position of base station 132 and mobile station 310, thedetermination as to whether the reported position associated with basestation 132 is sufficiently accurate may be based on any of a variety ofother factors. Such factors may include one or more of an estimatedcoverage area of base station 132, an uncertainty value associated withthe estimated position of mobile station 310, a previously determineduncertainty value associated with the reported position associated withbase station 132, and/or an amount of previous observations of one ormore signals transmitted by base station 132 at a plurality ofindependent positions within a coverage area of the base station.However, these are merely examples of other factors upon which thedetermination of whether the reported position associated with basestation 132 is sufficiently accurate may be based, and the scope ofclaimed subject matter is not limited in this respect.

In an aspect, the estimated coverage area of base station 132 mentionedabove may be based, at least in part, on a strength of one or moresignals transmitted by base station 132. The estimated coverage area forbase station 132 may further be estimated based on information providedby an almanac, and/or may be inferred from search window informationfrom a neighbor list, in another example aspect. In additional examples,the estimated coverage area for base station 132 may be based at leastin part on one or more range estimates to one or more neighbors, and/ormay be based at least in part on a density of base stations in aspecified area. Of course, these are merely example techniques forestimating a coverage area of a base station, and the scope of claimedsubject matter is not limited in this respect. Further, in anotheraspect, measurements obtained by mobile station 310 of signalstransmitted by base station 132 may be utilized to adjust a reportedcoverage area of base station 132, and/or may be utilized to indicatethat the reported coverage area of base station 132 is not reliable.

As previously discussed, if measurements obtained by mobile station 310of the signals transmitted by base station 132 at approximately thefirst point in time correlate relatively strongly with the calculatedrange to base station 132, the reported position associated with basestation 132 may be considered to be at least sufficiently accurate inaccordance with an accuracy metric. That is, the reported positionassociated with base station 132 may be said to be reasonable in lightof available information, and there may be said to be a relatively highdegree of agreement between the calculated range and the measurementsobtained from the signals transmitted by base station 132 atapproximately the first point in time, t1. On the other hand, ifmeasurements obtained by mobile station 310 at approximately the firstpoint in time do not have a high degree of agreement with the calculatedrange, the reported position may be assumed to not be sufficientlyaccurate in accordance with the accuracy metric. In such a case, thereported position may not be considered to be reasonable in light ofavailable information. In this circumstance, the reported position maybe deemed to be unreliable. In another aspect, whether a reportedposition associated with a base station is considered to be reasonablemay depend, at least in part, on a given application. For example, forestimating a position of a mobile station, if a measured range and acalculated range are within two meters of each other, the reportedposition may be considered to be reasonable. On the other hand, if themeasured range and the calculated range differ by more than two meters,the reported position may be considered to be unreasonable. Of course,any threshold value, such as 0.2 meters, 0.5 meters, 1 meter, 3 meters,5 meters, 10 meters, or value plus or minus a range, such as 1±0.2meters, etc., may be utilized in making determinations of reasonablenessfor reported positions of wireless transmitters, depending at least inpart on the particular application, and the scope of claimed subjectmatter is not limited in this respect.

At least in part in response to a determination that the reportedposition associated with base station 132 is not sufficiently accurate,an uncertainty factor may be determined for the reported position. Inone aspect, the uncertainly factor may be based, at least in part, on aresidual error value between the calculated range and a measured rangebetween the estimated position of mobile station 310 and the position ofbase station 132. Of course, in many situations, an actual and/oraccurate position of base station 132 may not be known. In such a case,the range between mobile station 310 and base station 132 may bemeasured, in an aspect, and/or the range may be estimated based onmeasurements obtained by mobile station 310 on signals transmitted frombase station 132. In another aspect, the range may be determined, atleast in part, based on known positions of other transmitters from whichmobile station 310 may receive signals. As used herein, the termmeasured range refers to a range between a mobile station and a wirelesstransmitter obtained through measurement and/or estimation techniquessuch as, for example, the techniques discussed. Further, in an aspect,measurement and/or estimation techniques for obtaining a measured rangemay not rely on a reported position of the wireless transmitter. Ofcourse, the scope of claimed subject matter is not limited to anyparticular measurement and/or estimation techniques mentioned herein. Ameasured range 311 is depicted in FIG. 3 between mobile station 310 andbase station 132.

In a further aspect, the uncertainty value determined above, based atleast in part on a residual error between the calculated range andmeasured range 311, whether measured range 311 is directly measured orwhether estimated in some manner, may be further refined as additionaldata points are gathered at other locations. For example, a mobilestation 320 may perform similar operations as those described above inconnection with mobile station 310. That is, a position (x2, y2, z2) formobile station 320 may be estimated at a time t2, and a range may becalculated between the reported position of base station 132 and theestimated position of mobile station 320. To determine whether thereported position associated with base station 132 is sufficientlyaccurate, mobile station 320 may obtain one or more measurements fromone or more signals transmitted by base station 132 at approximately thesecond point in time, t2.

In an aspect, if the obtained measurements have a significant degree ofagreement with the calculated range (degree of agreement is relativelylarge), the reported position associated with base station 132 may beconsidered to be at least sufficiently accurate, and the uncertaintyvalue generated in response to the residual error determined by mobilestation 310 for base station 132 may be reduced. If, however, theobtained measurements do not have a significant degree of agreement withthe calculated range between the reported position associated with basestation 132 and the estimated position of mobile station 320 (degree ofagreement is relatively small), the uncertainty value generated inresponse to the residual error determined by mobile station 310 for basestation 132 may be increased. In a further aspect, a second residualerror value may be determined based on the calculated range and measuredrange 321, whether the measured range is measured directly or estimatedbased at least in part on one or more measurements of one or moresignals transmitted by base station 132 at approximately the secondpoint in time, t2. If the additional residual error is relatively large,meaning there is a low degree of agreement between the calculated rangeand the obtained measurements (degree of agreement is relatively small),the uncertainty value associated with the reported position for basestation 132 may be increased, and if the additional residual error isrelatively small, meaning there is a high degree of agreement betweenthe calculated range and the obtained measurements (degree of agreementis relatively large), the uncertainty value associated with base station132 may be reduced.

Continuing with the example depicted in FIG. 3, the uncertainty valueassociated with the reported position associated with base station 132may continue to be refined as additional measurements are taken atlocation (x3, y3, z3) for mobile station 330 at, for example,approximately time t3 and at location (x4, y4, z4) for mobile station340 at, for example, approximately time t4. Third and fourth residualerrors may be determined based at least in part on calculated rangesbetween mobile stations 330 and 340 and base station 132, as well asbased at least in part on measured ranges 331 and 341. In general, thegreater the number of residual errors that are determined for variouslocations within a coverage area for base station 132, the more refinedthe uncertainty value may become for the position reported for basestation 132.

In another aspect, the bias and spread of the various residual errorvalues determined at the various locations within the coverage area ofbase station 132 may be used to correct future measurements involvingbase station 132. In an aspect, a correction factor may be determinedthat may allow future measurements using the reported position of basestation 132 to be more accurate. For example, a mobile station relyingon signals from base station 132 to obtain a position estimate mayutilize the uncertainty value and/or correction value associated withthe reported position of base station 132 to reduce the error in anyposition estimated through use of the signals from base station 132.

In another aspect, if the uncertainty value associated with the reportedposition of base station 132 exceeds a selected threshold, the reportedposition may be labeled as unreliable. For example, a base stationalmanac that includes an entry for base station 132 may also include anentry describing the reported position for base station 132 asunreliable. The determined uncertainly value may also be provided in thebase station almanac so that future mobile station position estimatesand/or other measurements involving base station 132 may make use of theuncertainty value to improve the accuracy of the position estimates orother measurements. In a further aspect, if the uncertainty valueexceeds a selected threshold, the reported position associated with basestation 132 may be removed from the almanac, although the scope ofclaimed subject matter is not limited in this respect.

FIG. 4 is a flow diagram of an example process for determining theintegrity of a reported position of a terrestrial wireless transmitter.At block 410, the reported position may be received at a mobile station.At block 420, a position of the mobile station may be estimated atapproximately a first point in time. At block 430, a range may becalculated between the reported position associated with the wirelesstransmitter and the estimated position of the mobile station. At block440, a determination may be made as to whether the reported positionassociated with the wireless transmitter is sufficiently accurate inaccordance with an accuracy metric based at least in part on thecalculated distance and based at least in part on one or moremeasurements related to one or more signals transmitted by the wirelesstransmitter at approximately the first point in time. Examples inaccordance with claimed subject matter may include all of, less than, ormore than blocks 410-440. Further, the order of blocks 410-440 is merelyan example order, and the scope of claimed subject matter is not limitedin this respect.

FIG. 5 is a flow diagram of an example process for ascertaining anuncertainty value associated with a reported position for a terrestrialwireless transmitter. At block 510 of this example, an uncertainty valuefor a reported position associated with the terrestrial wirelesstransmitter may be initialized, and at block 520, the variable “n” isinitialized to the value “1”. At block 530, an n^(th) residual errorvalue may be determined for the reported position of the wirelesstransmitter based at least in part on a calculated range between thewireless transmitter and a mobile station at an n^(th) point in time andfurther based at least in part on one or more measurements of one ormore signals transmitted by the wireless transmitter at approximatelythe n^(th) point in time. Additionally, at block 540, the uncertaintyvalue for the reported position of the wireless transmitter may beadjusted based at least in part on the determined residual error value(degree of agreement between the reported position and the one or moremeasurements). At block 550, the variable “n” is incremented, and theprocess returns to block 530, where additional residual error values maybe determined. For the present example, as additional residual errorvalues are determined over time and over a variety of locations within acoverage area of the wireless transmitter, the uncertainty valueassociated with the reported position of the wireless transmitter may berefined. In a further aspect, as described above, the bias and/or spreadof the residuals may be used to improve future mobile station positionestimates involving the wireless transmitter, and to improve otherfurther measurements involving the wireless transmitter. Examples inaccordance with claimed subject matter may include all of, less than, ormore than blocks 510-550. Further, the order of blocks 510-550 is merelyan example order, and the scope of claimed subject matter is not limitedin this respect.

FIG. 6 is a block diagram of an example of mobile station 150 that maybe adapted to perform any of the example techniques described herein.One or more transceivers 670 may be adapted to modulate an RF carriersignal with baseband information, such as voice or data, onto an RFcarrier, and demodulate a modulated RF carrier to obtain such basebandinformation. The one or more transceivers 670 may be adapted to receiveand transmit signals such as CDMA, GSM, Wi-Fi, Bluetooth, etc. from, forexample, wireless transmitters. An antenna 672 may be adapted totransmit a modulated RF carrier over a wireless communications link andreceive a modulated RF carrier over a wireless communications link.

A baseband processor 660 may be adapted to provide baseband informationfrom a processing unit (PU) 620 to transceiver 670 for transmission overa wireless communications link. Here, PU 620 may obtain such basebandinformation from an input device within a user interface 610. Basebandprocessor 660 may also be adapted to provide baseband information fromtransceiver 670 to PU 620 for transmission through an output devicewithin user interface 610.

User interface 610 may comprise a plurality of devices for inputting oroutputting user information such as voice or data. Such devices mayinclude, by way of non-limiting examples, a keyboard, a display, a touchscreen, a microphone, and a speaker.

Antennas 682 and 684 may be adapted to receive signals from SPSs. Forexample, antenna 682 may receive GPS signals and antenna 684 may receiveGalileo signals. A receiver 680 may be adapted to receive and demodulatesignals from an SPS, and provide demodulated information to correlator640. Correlator 640 may be adapted to derive correlation functions fromthe information provided by receiver 680. Correlator 640 may also beadapted to derive pilot-related correlation functions from informationrelating to pilot signals provided by transceiver 670. This informationmay be used by a mobile station to acquire wireless communicationsservices. Channel decoder 650 may be adapted to decode channel symbolsreceived from baseband processor 660 into underlying source bits. In oneexample where channel symbols comprise convolutionally encoded symbols,such a channel decoder may comprise a Viterbi decoder. In a secondexample, where channel symbols comprise serial or parallelconcatenations of convolutional codes, channel decoder 650 may comprisea turbo decoder.

A memory 630 may be adapted to store machine-readable instructions whichare executable to perform one or more of processes, implementations, orexamples which are described or suggested herein. PU 620 may be adaptedto access and execute such machine-readable instructions.

FIG. 7 is a schematic diagram illustrating an example computing andcommunications environment 700 that may include one or more devicesconfigurable to implement techniques and/or processes described, forexample, in connection with example techniques associated with FIGS.1-5. System 700 may include, for example, a first device 702, a seconddevice 704, and a third device 706, which may be operatively coupledtogether through a network 708.

First device 702, second device 704 and third device 706, as shown inFIG. 7, may be representative of any device, appliance or machine thatmay be configurable to exchange data over wireless communicationsnetwork 708. By way of example but not limitation, any of first device702, second device 704, or third device 706 may include: one or morecomputing devices and/or platforms, such as, e.g., a desktop computer, alaptop computer, a workstation, a server device, or the like; one ormore personal computing or communication devices or appliances, such as,e.g., a personal digital assistant, mobile communication device, or thelike; a computing system and/or associated service provider capability,such as, e.g., a database or data storage service provider/system, anetwork service provider/system, an Internet or intranet serviceprovider/system, a portal and/or search engine service provider/system,a wireless communication service provider/system; and/or any combinationthereof. Any of the first, second, and third devices 702, 704, and 706,respectively, may comprise one or more of a base station almanacdatabase server, a base station, and/or a mobile station in accordancewith the examples described herein.

Similarly, network 708, is representative of one or more communicationlinks, processes, and/or resources configurable to support the exchangeof data between at least two of first device 702, second device 704, andthird device 706. By way of example but not limitation, network 708 mayinclude wireless and/or wired communication links, telephone ortelecommunications systems, data buses or channels, optical fibers,terrestrial or satellite resources, local area networks, wide areanetworks, intranets, the Internet, routers or switches, and the like, orany combination thereof. As illustrated, for example, by the dashedlined box illustrated as being partially obscured by third device 706,there may be additional devices operatively coupled to network 708.

It is recognized that all or part of the various devices and networksshown in system 700, and the processes and methods as further describedherein, may be implemented using or otherwise including hardware,firmware, software, or any combination thereof.

Thus, by way of example but not limitation, second device 704 mayinclude at least one processing unit 720 that is operatively coupled toa memory 722 through a bus 728.

Processing unit 720 is representative of one or more circuitsconfigurable to perform at least a portion of a data computing procedureor process. By way of example but not limitation, processing unit 720may include one or more processors, controllers, microprocessors,microcontrollers, application specific integrated circuits, digitalsignal processors, programmable logic devices, field programmable gatearrays, and the like, or any combination thereof.

Memory 722 is representative of any data storage mechanism. Memory 722may include, for example, a primary memory 724 and/or a secondary memory726. Primary memory 724 may include, for example, a random accessmemory, read only memory, flash memory, etc. While illustrated in thisexample as being separate from processing unit 720, it should beunderstood that all or part of primary memory 724 may be provided withinor otherwise co-located/coupled with processing unit 720.

Secondary memory 726 may include, for example, the same or similar typeof memory as primary memory 724 and/or one or more data storage devicesor systems, such as, for example, a disk drive, an optical disc drive, atape drive, a solid state memory drive, etc. In certain implementations,secondary memory 726 may be operatively receptive of, or otherwiseconfigurable to couple to, a computer-readable medium 740.Computer-readable medium 740 may include, for example, any medium thatcan carry and/or make accessible data, code and/or instructions for oneor more of the devices in system 700. Computer-readable medium 740 mayalso be referred to as a storage medium.

Second device 704 may include, for example, a communication interface730 that provides for or otherwise supports the operative coupling ofsecond device 704 to at least network 708. By way of example but notlimitation, communication interface 730 may include a network interfacedevice or card, a modem, a router, a switch, a transceiver, and thelike.

Second device 704 may include, for example, an input/output 732.Input/output 732 is representative of one or more devices or featuresthat may be configurable to accept or otherwise introduce human and/ormachine inputs, and/or one or more devices or features that may beconfigurable to deliver or otherwise provide for human and/or machineoutputs. By way of example but not limitation, input/output device 732may include an operatively configured display, speaker, keyboard, mouse,trackball, touch screen, data port for wired and/or wirelesscommunications, etc.

The methodologies described herein may be implemented by various meansdepending upon applications according to particular examples. Forexample, such methodologies may be implemented in hardware, firmware,software, and/or combinations thereof. In an implementation involvinghardware, for example, a processing unit may be implemented within oneor more application specific integrated circuits (ASICs), digital signalprocessors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), field programmable gate arrays(FPGAs), processors, controllers, micro-controllers, microprocessors,electronic devices, other devices units designed to perform thefunctions described herein, and/or combinations thereof.

For an implementation involving firmware and/or software, themethodologies may be implemented with modules (e.g., procedures,functions, and so on) that perform the functions described herein. Anymachine-readable medium tangibly embodying instructions may be used inimplementing the methodologies described herein. For example, softwarecodes may be stored in a memory and executed by a processor unit. Memorymay be implemented within the processor unit or external to theprocessor unit. As used herein the term “memory” refers to any type oflong term, short term, volatile, nonvolatile, or other memory and is notto be limited to any particular type of memory or number of memories, ortype of media upon which memory is stored.

Instructions as referred to herein relate to expressions which representone or more logical operations. For example, instructions may be“machine-readable” by being interpretable by a machine for executing oneor more operations on one or more data objects. However, this is merelyan example of instructions and claimed subject matter is not limited inthis respect. In another example, instructions as referred to herein mayrelate to encoded commands which are executable by a processing circuithaving a command set which includes the encoded commands. Such aninstruction may be encoded in the form of a machine language understoodby the processing circuit. Again, these are merely examples of aninstruction and claimed subject matter is not limited in this respect.

Storage medium as referred to herein relates to media capable ofmaintaining expressions which are perceivable by one or more machines.For example, a storage medium may comprise one or more storage devicesfor storing machine-readable instructions and/or information. Suchstorage devices may comprise media types including, for example,magnetic, optical or semiconductor storage media. Such storage devicesmay also comprise any type of long term, short term, volatile ornon-volatile memory devices. However, these are merely examples of astorage medium, and claimed subject matter is not limited in theserespects.

Some portions of the detailed description included herein may bepresented in terms of algorithms or symbolic representations ofoperations on binary digital signals stored within a memory of aspecific apparatus or special purpose computing device or platform. Inthe context of this particular specification, the term specificapparatus or the like includes a general purpose computer once it isprogrammed to perform particular operations pursuant to instructionsfrom program software. Algorithmic descriptions or symbolicrepresentations are examples of techniques used by those of ordinaryskill in the signal processing or related arts to convey the substanceof their work to others skilled in the art. An algorithm is here, andgenerally, considered to be a self-consistent sequence of operations orsimilar signal processing leading to a desired result. In this context,operations or processing involve physical manipulation of physicalquantities. Typically, although not necessarily, such quantities maytake the form of electrical or magnetic signals capable of being stored,transferred, combined, compared or otherwise manipulated. It has provenconvenient at times, principally for reasons of common usage, to referto such signals as bits, data, values, elements, symbols, characters,terms, numbers, numerals, or the like. It should be understood, however,that all of these or similar terms are to be associated with appropriatephysical quantities and are merely convenient labels. Unlessspecifically stated otherwise, it is appreciated that throughout thisspecification discussions utilizing terms such as “processing,”“computing,” “calculating,” “determining” or the like refer to actionsor processes of a specific apparatus, such as a special purpose computeror a similar special purpose electronic computing device. In the contextof this specification, therefore, a special purpose computer or asimilar special purpose electronic computing device is capable ofmanipulating or transforming signals, typically represented as physicalelectronic or magnetic quantities within memories, registers, or otherinformation storage devices, transmission devices, or display devices ofthe special purpose computer or similar special purpose electroniccomputing device.

Wireless communication techniques described herein may be in connectionwith various wireless communication networks such as a wireless widearea network (WWAN), a wireless local area network (WLAN), a wirelesspersonal area network (WPAN), and so on. The terms network and systemmay be used interchangeably herein. A WWAN may be a Code DivisionMultiple Access (CDMA) network, a Time Division Multiple Access (TDMA)network, a Frequency Division Multiple Access (FDMA) network, anOrthogonal Frequency Division Multiple Access (OFDMA) network, aSingle-Carrier Frequency Division Multiple Access (SC-FDMA) network, aLong Term Evolution (LTE) network, or any combination of the abovenetworks, and so on. A CDMA network may implement one or more radioaccess technologies (RATs) such as cdma2000, Wideband-CDMA (W-CDMA), toname just a few radio technologies. Here, cdma2000 may includetechnologies implemented according to IS-95, IS-2000, and IS-856standards. A TDMA network may implement Global System for MobileCommunications (GSM), Digital Advanced Mobile Phone System (D-AMPS), orsome other RAT. GSM and W-CDMA are described in documents from aconsortium named “3rd Generation Partnership Project” (3GPP). Cdma2000is described in documents from a consortium named “3rd GenerationPartnership Project 2” (3GPP2). 3GPP and 3GPP2 documents are publiclyavailable. A WLAN may comprise an IEEE 802.11x network, and a WPAN maycomprise a Bluetooth network, an IEEE 802.15x network, for example.Wireless communication implementations described herein may also be usedin connection with any combination of WWAN, WLAN and/or WPAN.

Techniques described herein may be used with any one or more of severalSPSs. A satellite positioning system (SPS) typically includes a systemof transmitters positioned to enable entities to determine theirlocation on or above the Earth based, at least in part, on signalsreceived from the transmitters. Such a transmitter typically transmits asignal marked with a repeating pseudo-random noise (PN) code of a setnumber of chips and may be located on ground based control stations,user equipment and/or space vehicles. In a particular example, suchtransmitters may be located on Earth orbiting satellite vehicles (SVs).For example, a SV in a constellation of Global Navigation SatelliteSystem (GNSS) such as Global Positioning System (GPS), Galileo, Glonassor Compass may transmit a signal marked with a PN code that isdistinguishable from PN codes transmitted by other SVs in theconstellation (e.g., using different PN codes for each satellite as inGPS or using the same code on different frequencies as in Glonass). Inaccordance with certain aspects, the techniques presented herein are notrestricted to global systems (e.g., GNSS) for SPS. For example, thetechniques provided herein may be applied to or otherwise enabled foruse in various regional systems, such as, e.g., Quasi-Zenith SatelliteSystem (QZSS) over Japan, Indian Regional Navigational Satellite System(IRNSS) over India, Beidou over China, etc., and/or various augmentationsystems (e.g., an Satellite Based Augmentation System (SBAS)) that maybe associated with or otherwise enabled for use with one or more globaland/or regional navigation satellite systems. By way of example but notlimitation, an SBAS may include an augmentation system(s) that providesintegrity information, differential corrections, etc., such as, e.g.,Wide Area Augmentation System (WAAS), European Geostationary NavigationOverlay Service (EGNOS), Multi-functional Satellite Augmentation System(MSAS), GPS Aided Geo Augmented Navigation or GPS and Geo AugmentedNavigation system (GAGAN), and/or the like. Thus, as used herein an SPSmay include any combination of one or more global and/or regionalnavigation satellite systems and/or augmentation systems, and SPSsignals may include SPS, SPS-like, and/or other signals associated withsuch one or more SPS.

Furthermore, such techniques may be used with positioning determinationsystems that utilize pseudolites or a combination of satellites andpseudolites. Pseudolites may comprise ground-based transmitters thatbroadcast a PRN code or other ranging code (e.g., similar to a GPS orCDMA cellular signal) modulated on an L-band (or other frequency)carrier signal, which may be synchronized with GPS time. Such atransmitter may be assigned a unique PRN code so as to permitidentification by a remote receiver. Pseudolites may be useful insituations where SPS signals from an SV might be unavailable, such as intunnels, mines, buildings, urban canyons or other enclosed areas.Another implementation of pseudolites is known as radio-beacons. Theterm satellite, as used herein, is intended to include pseudolites,equivalents of pseudolites, and possibly others. The term SPS signals,as used herein, is intended to include SPS-like signals from pseudolitesor equivalents of pseudolites.

As used herein, a mobile station (MS) refers to a device such as acellular or other wireless communication device, personal communicationsystem (PCS) device, personal navigation device (PND), PersonalInformation Manager (PIM), Personal Digital Assistant (PDA), laptop orother suitable mobile device which is capable of receiving wirelesscommunication and/or navigation signals. The term “mobile station” isalso intended to include devices which communicate with a personalnavigation device (PND), such as by short-range wireless, infrared,wireline connection, or other connection—regardless of whether satellitesignal reception, assistance data reception, and/or position-relatedprocessing occurs at the device or at the PND. Also, “mobile station” isintended to include all devices, including wireless communicationdevices, computers, laptops, etc. which are capable of communicationwith a server, such as via the Internet, Wi-Fi, or other network, andregardless of whether satellite signal reception, assistance datareception, and/or position-related processing occurs at the device, at aserver, or at another device associated with the network. Any operablecombination of the above are also considered a “mobile station.”

If implemented in firmware and/or software, the functions may be storedas one or more instructions or code on a computer-readable medium.Examples include computer-readable media encoded with a data structureand computer-readable media encoded with a computer program. Acomputer-readable medium may take the form of an article of manufacture.Computer-readable media includes physical computer storage media. Astorage medium may be any available medium that can be accessed by acomputer. By way of example, and not limitation, such computer-readablemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage, semiconductor storage, or other storagedevices, or any other medium that can be used to store desired programcode in the form of instructions or data structures and that can beaccessed by a computer; disk and disc, as used herein, includes compactdisc (CD), laser disc, optical disc, digital versatile disc (DVD),floppy disk and Blu-ray disc where disks usually reproduce datamagnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media.

In addition to storage on computer-readable medium, instructions and/ordata may be provided as signals on transmission media included in acommunication apparatus. For example, a communication apparatus mayinclude a transceiver having signals indicative of instructions anddata. The instructions and data are configured to cause one or moreprocessors to implement the functions outlined in the claims. That is,the communication apparatus includes transmission media with signalsindicative of information to perform disclosed functions. At a firsttime, the transmission media included in the communication apparatus mayinclude a first portion of the information to perform the disclosedfunctions, while at a second time the transmission media included in thecommunication apparatus may include a second portion of the informationto perform the disclosed functions.

While there has been illustrated and described what are presentlyconsidered to be example features, it will be understood by thoseskilled in the art that various other modifications may be made, andequivalents may be substituted, without departing from claimed subjectmatter. Additionally, many modifications may be made to adapt aparticular situation to the teachings of claimed subject matter withoutdeparting from the central concept described herein. Therefore, it isintended that claimed subject matter not be limited to the particularexamples disclosed, but that such claimed subject matter may alsoinclude all aspects falling within the scope of the appended claims, andequivalents thereof.

1. A method, comprising: receiving a reported position associated with awireless transmitter; estimating a position of a mobile station at afirst point in time; calculating a range between the reported positionassociated with the wireless transmitter and the estimated position ofthe mobile station; and determining whether the reported positionassociated with the wireless transmitter is sufficiently accurate inaccordance with an accuracy metric based at least in part on thecalculated range and based at least in part on one or more measurementsrelated to one or more signals transmitted by the wireless transmitterat approximately the first point in time.
 2. The method of claim 1,wherein the one or more measurements related to the one or more signalstransmitted by the wireless transmitter are performed by the mobilestation.
 3. The method of claim 1, wherein said receiving the reportedposition associated with the wireless transmitter comprises receivingthe reported position from the wireless transmitter.
 4. The method ofclaim 1, wherein said receiving the reported position associated withthe wireless transmitter comprises receiving an almanac of informationrelated to a plurality of transmitters.
 5. The method of claim 1,wherein said receiving the reported position associated with thewireless transmitter comprises receiving an estimated position of anantenna of the wireless transmitter.
 6. The method of claim 1, whereinsaid receiving the reported position associated with the wirelesstransmitter comprises receiving an estimated position of a center of acoverage area of the wireless transmitter.
 7. The method of claim 1,wherein said estimating the position of the mobile station at the firstpoint in time comprises estimating the position of the mobile stationwithin the mobile station.
 8. The method of claim 1, wherein saidestimating the position of the mobile station at the first point in timecomprises estimating the position of the mobile station at a networkserver.
 9. The method of claim 1, wherein said determining whether thereported position associated with the wireless transmitter issufficiently accurate is based, at least in part, on one or more of: anestimated coverage area of the wireless transmitter; an uncertaintyvalue associated with the estimated position of the mobile station; anuncertainty value associated with the reported position; a timingparameter for at least one of said one or more signals transmitted bythe wireless transmitter and received at the mobile station; a strengthof at least one of said one or more signals transmitted by the wirelesstransmitter and received at the mobile station; and/or an amount ofprevious observations of one or more signals transmitted by the wirelesstransmitter at a plurality of independent positions within a coveragearea of the wireless transmitter.
 10. The method of claim 9, whereinsaid estimated coverage area of the wireless transmitter is based, atleast in part, on said strength of said at least one of said one or moresignals transmitted by the wireless transmitter and received at themobile station, an estimated coverage area provided by a base stationalmanac, information inferred from search windows from a neighbor list,one or more range estimates to one or more neighbors, and/or a densityof base stations in a specified area.
 11. The method of claim 1, furthercomprising adjusting a reported coverage area of the wirelesstransmitter and/or indicating that the reported coverage area of thewireless transmitter is not reliable based at least in part on said oneor more measurements.
 12. The method of claim 1, further comprisingassigning an uncertainty value to the reported position associated withthe wireless transmitter based at least in part on the calculated rangeand based at least in part on said one or more measurements.
 13. Themethod of claim 12, further comprising adjusting said uncertainty valuebased at least in part on a degree of agreement between said reportedposition and said one or more measurements.
 14. The method of claim 13,wherein said adjusting said uncertainty value comprises increasing theuncertainly value if the degree of agreement between said reportedposition and said one or more measurements is relatively small.
 15. Themethod of claim 13, wherein said adjusting said uncertainty valuecomprises decreasing the uncertainly value if the degree of agreementbetween said reported position and said one or more measurements isrelatively large.
 16. The method of claim 13, further comprisinglabeling the reported position of the wireless transmitter as unreliableif the uncertainty value exceeds a specified threshold.
 17. A mobilestation, comprising: a receiver to receive a reported positionassociated with a wireless transmitter, the receiver further to receiveone or more signals transmitted by the wireless transmitter atapproximately a first point in time; and a processing unit to estimateat least in part a position of the mobile station at the first point intime, the processing unit further to calculate at least in part a rangebetween the reported position associated with the wireless transmitterand the estimated position of the mobile station, and the processingunit further to determine at least in part whether the reported positionassociated with the wireless transmitter is sufficiently accurate inaccordance with an accuracy metric based at least in part on thecalculated range and based at least in part on one or more measurementsrelated to said one or more signals transmitted by the wirelesstransmitter.
 18. The mobile station of claim 17, wherein the one or moremeasurements related to the one or more signals transmitted by thewireless transmitter are performed by the mobile station.
 19. The mobilestation of claim 17, said receiver to receive the reported positionassociated with the wireless transmitter by receiving the reportedposition from the wireless transmitter.
 20. The mobile station of claim17, said receiver to receive the reported position associated with thewireless transmitter by receiving an almanac of information related to aplurality of transmitters.
 21. The mobile station of claim 17, saidreceiver to receive the reported position associated with the wirelesstransmitter by receiving an estimated position of an antenna of thewireless transmitter.
 22. The mobile station of claim 17, said receiverto receive the reported position associated with the wirelesstransmitter by receiving an estimated position of a center of a coveragearea of the wireless transmitter.
 23. The mobile station of claim 17,said processing unit to determine whether the reported positionassociated with the wireless transmitter is sufficiently accurate based,at least in part, on one or more of: an estimated coverage area of thewireless transmitter; an uncertainty value associated with the estimatedposition of the mobile station; an uncertainty value associated with thereported position; a timing parameter for at least one of said one ormore signals transmitted by the wireless transmitter and received at themobile station; a strength of at least one of said one or more signalstransmitted by the wireless transmitter and received at the mobilestation; and/or an amount of previous observations of one or moresignals transmitted by the wireless transmitter at a plurality ofindependent positions within a coverage area of the wirelesstransmitter.
 24. The mobile station of claim 23, said processing unit toestimate the coverage area of the wireless transmitter based, at leastin part, on said strength of said at least one of said one or moresignals transmitted by the wireless transmitter and received at themobile station, an estimated coverage area provided by a base stationalmanac, information inferred from search windows from a neighbor list,one or more range estimates to one or more neighbors, and/or a densityof base stations in a specified area.
 25. The mobile station of claim17, said processing unit further to adjust a reported coverage area ofthe wireless transmitter and/or to indicate that the reported coveragearea of the wireless transmitter is not reliable based at least in parton said one or more measurements.
 26. The mobile station of claim 17,said processing unit further to assign an uncertainty value to thereported position associated with the wireless transmitter based atleast in part on the calculated range and based at least in part on saidone or more measurements.
 27. The mobile station of claim 26, saidprocessing unit to adjust said uncertainty value based at least in parton a degree of agreement between said reported position and said one ormore measurements.
 28. The mobile station of claim 27, said processingunit to adjust said uncertainty value by increasing the uncertainlyvalue if the degree of agreement between said reported position and saidone or more measurements is relatively small.
 29. The mobile station ofclaim 27, said processing unit to adjust said uncertainty value bydecreasing the uncertainly value if the degree of agreement between saidreported position and said one or more measurements is relatively large.30. The mobile station of claim 27, said processing unit further tolabel the reported position of the wireless transmitter as unreliable ifthe uncertainty value exceeds a specified threshold.
 31. An apparatus,comprising: means for receiving a reported position associated with awireless transmitter; means for receiving at a mobile station one ormore signals transmitted by the wireless transmitter at approximately afirst point in time; means for estimating a position of the mobilestation at the first point in time; means for calculating a rangebetween the reported position associated with the wireless transmitterand the estimated position of the mobile station; and means fordetermining whether the reported position associated with the wirelesstransmitter is sufficiently accurate in accordance with an accuracymetric based at least in part on the calculated range and based at leastin part on one or more measurements related to said one or more signalstransmitted by the wireless transmitter.
 32. The apparatus of claim 31,wherein the one or more measurements related to the one or more signalstransmitted by the wireless transmitter are performed by the mobilestation.
 33. The apparatus of claim 31, wherein said means for receivingthe reported position associated with the wireless transmitter comprisesmeans for receiving the reported position from the wireless transmitter.34. The apparatus of claim 31, wherein said means for receiving thereported position associated with the wireless transmitter comprisesmeans for receiving an almanac of information related to a plurality oftransmitters.
 35. The apparatus of claim 31, wherein said means forreceiving the reported position associated with the wireless transmittercomprises means for receiving an estimated position of an antenna of thewireless transmitter.
 36. The apparatus of claim 31, wherein said meansfor receiving the reported position associated with the wirelesstransmitter comprises means for receiving an estimated position of acenter of a coverage area of the wireless transmitter.
 37. The apparatusof claim 31, wherein said means for estimating the position of themobile station at the first point in time comprises means forcalculating the estimated position of the mobile station within themobile station.
 38. The apparatus of claim 31, wherein said means forestimating the position of the mobile station at the first point in timecomprises means for receiving an estimated position of the mobilestation calculated at a network server.
 39. The apparatus of claim 31,wherein said means for determining whether the reported positionassociated with the wireless transmitter is sufficiently accuratecomprises means for making the determination based, at least in part, onone or more of: an estimated coverage area of the wireless transmitter;an uncertainty value associated with the estimated position of themobile station; an uncertainty value associated with the reportedposition; a timing parameter for at least one of said one or moresignals transmitted by the wireless transmitter and received at themobile station; a strength of at least one of said one or more signalstransmitted by the wireless transmitter and received at the mobilestation; and/or an amount of previous observations of one or moresignals transmitted by the wireless transmitter at a plurality ofindependent positions within a coverage area of the wirelesstransmitter.
 40. The apparatus of claim 39, wherein said estimatedcoverage area of the wireless transmitter is based, at least in part, onsaid strength of said at least one of said one or more signalstransmitted by the wireless transmitter and received at the mobilestation, an estimated coverage area provided by a base station almanac,information inferred from search windows from a neighbor list, one ormore range estimates to one or more neighbors, and/or a density of basestations in a specified area.
 41. The apparatus of claim 31, furthercomprising means for adjusting a reported coverage area of the wirelesstransmitter and/or means for indicating that the reported coverage areaof the wireless transmitter is not reliable based at least in part onsaid one or more measurements.
 42. The apparatus of claim 31, furthercomprising means for assigning an uncertainty value to the reportedposition associated with the wireless transmitter based at least in parton the calculated range and based at least in part on said one or moremeasurements.
 43. The apparatus of claim 42, further comprising meansfor adjusting said uncertainty value based at least in part on a degreeof agreement between said reported position and said one or moremeasurements.
 44. The apparatus of claim 43, wherein said means foradjusting said uncertainty value comprises means for increasing theuncertainly value if the degree of agreement between said reportedposition and said one or more measurements is relatively small.
 45. Theapparatus of claim 43, wherein said means for adjusting said uncertaintyvalue comprises means for decreasing the uncertainly value if the degreeof agreement between said reported position and said one or moremeasurements is relatively large.
 46. The apparatus of claim 43, furthercomprising means for labeling the wireless transmitter as unreliable ifthe uncertainty value exceeds a specified threshold.
 47. An article,comprising: a storage medium having stored thereon instructions that, ifexecuted by a processing unit of a mobile station, enable the processingunit to: estimate a position of the mobile station at a first point intime; calculate a range between a reported position associated with awireless transmitter and the estimated position of the mobile station;and determine whether the reported position associated with the wirelesstransmitter is sufficiently accurate in accordance with an accuracymetric based at least in part on the calculated range and based at leastin part on one or more measurements related to one or more signalstransmitted by the wireless transmitter at approximately the first pointin time.
 48. The article of claim 47, wherein the one or moremeasurements related to the one or more signals transmitted by thewireless transmitter are performed by the mobile station.
 49. Thearticle of claim 47, wherein the storage medium has stored thereonfurther instructions that, if executed, further enable the processingunit to receive the reported position associated with the wirelesstransmitter by receiving the reported position from the wirelesstransmitter.
 50. The article of claim 47, wherein the storage medium hasstored thereon further instructions that, if executed, further enablethe processing unit to receive the reported position associated with thewireless transmitter by receiving an almanac of information related to aplurality of transmitters.
 51. The article of claim 47, wherein thestorage medium has stored thereon further instructions that, ifexecuted, further enable the processing unit to receive the reportedposition associated with the wireless transmitter by receiving anestimated position of an antenna of the wireless transmitter.
 52. Thearticle of claim 47, wherein the storage medium has stored thereonfurther instructions that, if executed, further enable the processingunit to receive the reported position associated with the wirelesstransmitter by receiving an estimated position of a center of a coveragearea of the wireless transmitter.
 53. The article of claim 47, whereinthe storage medium has stored thereon further instructions that, ifexecuted, further enable the processing unit to determine whether thereported position associated with the wireless transmitter issufficiently accurate by making the determination based, at least inpart, on one or more of: an estimated coverage area of the wirelesstransmitter; an uncertainty value associated with the estimated positionof the mobile station; an uncertainty value associated with the reportedposition; a timing parameter for at least one of said one or moresignals transmitted by the wireless transmitter and received at themobile station; a strength of at least one of said one or more signalstransmitted by the wireless transmitter and received at the mobilestation; and/or an amount of previous observations of one or moresignals transmitted by the wireless transmitter at a plurality ofindependent positions within a coverage area of the wirelesstransmitter.
 54. The article of claim 53, wherein said estimatedcoverage area of the wireless transmitter is based, at least in part, onsaid strength of said at least one of said one or more signalstransmitted by the wireless transmitter and received at the mobilestation, an estimated coverage area provided by a base station almanac,information inferred from search windows from a neighbor list, one ormore range estimates to one or more neighbors, and/or a density of basestations in a specified area.
 55. The article of claim 47, wherein thestorage medium has stored thereon further instructions that, ifexecuted, further enable the processing unit to adjust a reportedcoverage area of the wireless transmitter and/or to indicate that thereported coverage area of the wireless transmitter is not reliable basedat least in part on said one or more measurements.
 56. The article ofclaim 47, wherein the storage medium has stored thereon furtherinstructions that, if executed, further enable the processing unit toassign an uncertainty value to the reported position associated with thewireless transmitter based at least in part on the calculated range andbased at least in part on said one or more measurements.
 57. The articleof claim 56, wherein the storage medium has stored thereon furtherinstructions that, if executed, further enable the processing unit toadjust said uncertainty value based at least in part on a degree ofagreement between said reported position and said one or moremeasurements.
 58. The article of claim 57, wherein the storage mediumhas stored thereon further instructions that, if executed, furtherenable the processing unit to adjust said uncertainty value byincreasing the uncertainly value if the degree of agreement between saidreported position and said one or more measurements is relatively small.59. The article of claim 57, wherein the storage medium has storedthereon further instructions that, if executed, further enable theprocessing unit to adjust said uncertainty value by decreasing theuncertainly value if the degree of agreement between said reportedposition and said one or more measurements is relatively large.
 60. Thearticle of claim 57, wherein the storage medium has stored thereonfurther instructions that, if executed, further enable the processingunit to label the reported position of the wireless transmitter asunreliable if the uncertainty value exceeds a specified threshold.